Laundry treating machines capable of carrying out a drying process on laundry generally comprise a casing that houses a laundry container, like a rotating drum, where laundry to be treated is received, a basement portion having seats for receiving machine operational devices, and an air circuit for carrying out drying operation by circulating hot air through the laundry container. Air circulating means and heating means are provided in the air circuit for circulating and heating drying air, respectively. In condenser type dryers, condensing means are further provided in the air circuit for removing moisture from drying air passing through articles to be treated thereby allowing said air to be recirculated cyclically within the air circuit. Moisture removed from articles is either collected in a tank periodically emptied by a user or it is directly exhausted by a pipe connected to a waste water net.
Washing-drying appliances, i.e. appliances provided for performing articles washing and drying operations in a single machine are also known and generally comprise a water circuit including pumping means for allowing washing water to be supplied to a laundry treating chamber and a drying arrangement as described before for drying laundry.
In the following description the invention will be disclosed with particular reference to a machine suitable for carrying out a drying operation on laundry such as a laundry drying machine or a washing-drying machine. However, in general, principles of the invention may be applied to a laundry treating appliance, for example in cases when an air flow is needed to cool machine operating devices or part thereof.
In a known condenser type laundry dryer, means for condensing moisture removed by articles are configured in many different ways. Typical examples comprise an air-air heat exchanger or an evaporator of a heat pump circuit incorporated within the dryer. Such condensing means or components thereof require cooling in order to constantly provide a cold surface where wet drying air can be condensed or to remove heat produced by said components, like a compressor in a heat pump circuit. Normally, air taken from dryer machine surroundings is used as cooling means of a condenser or components thereof. For this reason a plurality of conduits are provided on the lower portion of the laundry treating machine and, generally, a basement portion is appropriately designed to form at least a portion of cooling conduits.
In prior art laundry drying machines such cooling conduits comprise complicated air paths very often including joints, provided for changing path direction, that undesirably cause high flow resistance thereby compromising the overall machine performance.
A further drawback of known prior art laundry drying machine exists in that, when direction of an air path should be changed, a mere chamber is provided where air flow is moved from one direction to another practically without any guidance but only by means of a pressure difference.
Another drawback of prior art laundry drying machines as described above is high noise produced by cooling air circulating through conduits having complex and tortuous paths. This undesired noise is particularly disadvantageous because it prevents the appliance from being used during night hours and/or being placed close to rooms where silence is needed, such as bedrooms.